Entrance Exams
Govt. Exams
Radial arrangement is characteristic of monocot roots where xylem and phloem alternate on different radii. When they're on the same radii, it's called conjoint arrangement.
In monocot roots, the pericycle is usually uniseriate and gives rise to lateral roots, unlike in dicots where it's multiseriate.
In a young dicot stem, the sequence from outside is: cuticle, epidermis, cortex (containing hypodermis and endodermis), vascular bundles, and central pith.
The Casparian strip in endodermis is impregnated with suberin, making it impermeable to water and solutes, thus forcing them through the endodermal cells.
Tracheids are elongated, unicellular structures with tapering end walls and pits, unlike vessels which are multicellular with perforated end plates.
The spongy mesophyll contains intercellular spaces and is located below the palisade layer, facilitating gas exchange through stomata.
C4 plants exhibit Kranz anatomy where mesophyll cells and bundle sheath cells are specialized for different aspects of photosynthesis.
The endodermis contains the Casparian strip, which regulates the movement of water and solutes into the vascular cylinder.
Companion cells are specialized parenchymatous cells that remain alive and are attached to sieve tube elements in the phloem.
Dicot stems have vascular bundles arranged in a ring or eustele pattern, whereas monocots have scattered bundles.